Hermetically bonded glass packages and casings are increasingly popular for application to electronics and other devices that may benefit from a hermetic environment for sustained operation. Exemplary devices which may benefit from hermetic packaging include televisions, sensors, optical devices, organic light emitting diode (OLED) displays, 3D inkjet printers, solid-state lighting sources, and photovoltaic structures.
Glass, ceramic, and/or glass-ceramic substrates have been traditionally sealed by placing the substrates in a furnace, with or without an epoxy or other sealing material. However, the furnace typically operates at high processing temperatures which are unsuitable for many devices, such as OLEDs. For example, OLEDs generally must be processed at temperatures less than about 100° C., or even less than about 85° C., to protect the heat-sensitive components.
Other prior art methods include placing an absorbing layer or glass frit between the substrates. However, the addition of such layers can complicate the sealing process, introduce contaminants, and/or increase the operation cost. Glass frit is also often processed at higher temperatures unsuitable for devices such as OLEDs and/or may produce undesirable gasses upon sealing.
Glass substrates have been hermetically sealed by Applicant without an intermediate layer using ultrafast lasers. However, these direct glass-to-glass methods have only been successful thus far with glasses having a low coefficient of thermal expansion (CTE) (e.g., about 4 ppm/° C. or less). Similarly, glass frit methods have also traditionally been used to seal only low expansion glasses.
Attempts to seal high expansion glasses have thus been unsuccessful, are limited by a low speed (about 10 mm/s or less), and/or require substrate heating with increased speeds (about 20 mm/s), all of which can result in higher hermetic package manufacturing time, cost, and/or complexity. Accordingly, it would be advantageous to provide methods for welding high-CTE (e.g., >5 ppm/° C.) substrates at higher speeds and lower temperatures, which may, among other advantages, decrease manufacturing costs and/or increase production rate. The resulting sealed packages can be used to protect a wide array of electronics and other devices, such as OLEDs.